1. Field of the Invention
The present invention relates to an optical information processing apparatus for use in optical computing, optical image processing, and the like.
2. Description of Prior Art
For example, the invention disclosed in the specification of Japanese Patent Application No. H10-113148 is an example of an integrated optical information processing apparatus in which light emitting devices are bonded onto a semiconductor arithmetic circuit chip to form a light emitting device array. The structure of the conventional optical information processing apparatus is illustrated in FIG. 1. In FIG. 1, reference numeral 63 denotes a semiconductor light emitting diode, reference numeral 14 a diffraction type collimator lens, reference numeral 15 a diffraction type focusing lens, reference numeral 16 a glass substrate provided with diffraction type optical devices, reference numeral 17 a semiconductor arithmetic circuit chip, reference numeral 18 a light emitting device driving electrode, reference numeral 19 a light receiving device, reference numeral 64 a gold bump, reference numeral 23 an input signal light beam, reference numeral 24 an output signal light beam, reference numeral 61 a cylindrical glass, and reference numeral 62 a light blocking resin.
The operation of the conventional optical information processing apparatus having such a structure as described above will now be described by illustrating the operation of one pixel among a plurality of arrays. First, the input signal light beam 23 is focused by the diffraction type focusing lens 15 provided on the glass substrate 16 provided with diffraction type optical devices onto the light receiving device 19 provided on the semiconductor arithmetic circuit chip 17 through the cylindrical glass 61. Thus, the input signal light beam 23 is incident upon the light receiving device 19. The light receiving device 19 converts the incident input signal light beam 23 into an electric signal. The semiconductor arithmetic circuit chip 17 receives as its input signal the converted electric signal from the light receiving device 19, and performs an arithmetic operation. The result of the arithmetic operation is output to the light emitting device driving electrode 18 as an electric signal. The electric output signal which is output to the light emitting device driving electrode 18 is then applied to the semiconductor light emitting diode 63 via the gold bump 64, and a current flows through the semiconductor light emitting diode 63 according to the electric output signal. The semiconductor light emitting diode 63 converts the electric output signal into the output signal light beam 24 according to the result of the arithmetic operation. The output signal light beam 24 from the semiconductor light emitting diode 63 is output through the diffraction type collimator lens 14 provided on the glass substrate 16 provided with diffraction type optical devices while suppressing the spatial divergence thereof. The light blocking resin 62 blocks light from a side surface of the semiconductor light emitting diode 63 so that light from the side surface of the semiconductor light emitting diode 63 is not incident upon adjacent light receiving devices 19.
However, such a conventional structure as described above has the following problems. When forming the light emitting device array by bonding the semiconductor light emitting diodes 63 onto the respective light emitting device driving electrodes 18, the bonding is performed while positionally aligning the individual semiconductor light emitting diodes 63 with respect to the respective light emitting device driving electrodes 18. As a result, as the number of pixels provided in an array increases, the number of misaligned semiconductor light emitting diodes 63 increases. Therefore, it is difficult to produce a light emitting device array including the semiconductor light emitting diodes 63 with a good precision.
Moreover, the cylindrical glasses 61 are bonded onto the respective light receiving devices 19 while positionally aligning the cylindrical glasses 61 with respect to the respective light receiving devices 19. As a result, as the number of pixels provided in an array increases, the number of misaligned cylindrical glasses 61 increases. Therefore, it is difficult to provide the array of cylindrical glasses 61 respectively defining optical paths on the light receiving devices 19 with a good precision.
Furthermore, with the light blocking technique using the light blocking resin 62, the light blocking effect is reduced as the interval between each semiconductor light emitting diode 63 and an adjacent light receiving device 19 is reduced. Therefore, it is difficult to reduce the pixel-to-pixel interval of the conventional optical information processing apparatus having such a structure as described above, and thus to increase the integration density of, and thereby reducing the size of, the optical information processing apparatus.
In order to solve these problems in the prior art, the present invention provides an optical information processing apparatus comprising a light emitting device array provided on a semiconductor arithmetic circuit chip, the light emitting device array comprising light emitting devices which are embedded in through holes in a silicon substrate. In addition to such a structure, the optical information processing apparatus of the present invention may additionally comprise a substrate provided with diffraction type optical devices, and further through holes provided in the silicon substrate for defining optical paths for light receiving devices.
Thus, an array of light emitting devices and optical paths for light receiving devices can be easily formed on the semiconductor arithmetic circuit chip with a good precision, thereby providing a small-sized integrated optical information processing apparatus having a large number of pixels.
According to a first aspect of the present invention, there is provided an optical information processing apparatus, comprising: a semiconductor arithmetic circuit chip; and a light emitting device array integrated onto the semiconductor arithmetic circuit chip, the light emitting device array comprising a substrate (e.g., a silicon substrate) having a through hole and a light emitting device embedded in the through hole. This apparatus functions as follows. The semiconductor arithmetic circuit chip performs an arithmetic operation. The result of the arithmetic operation is applied as an electric output signal to the light emitting device which is embedded in the through hole in the substrate which forms a part of the light emitting device array. The light emitting device is operable to convert the electric output signal into an output signal light beam and output the obtained light beam.
Thus, according to the present invention, it is possible to realize a small-sized integrated optical information processing apparatus having a high pixel density and a large number of pixels by employing the light emitting device array in which the light emitting devices are embedded in the through holes in the silicon substrate.
According to a second aspect of the present invention, there is provided an optical information processing apparatus, comprising: a semiconductor arithmetic circuit chip; a light emitting device array integrated onto the semiconductor arithmetic circuit chip; and a diffraction type optical device integrated onto the light emitting device array, the light emitting device array comprising a substrate having a through hole and a light emitting device embedded in the through hole. The diffraction type optical device functions to focus an input signal light beam and to suppress spatial divergence of the output signal light beam from the light emitting device.
According to a third aspect of the present invention, a light receiving device is provided on the semiconductor arithmetic circuit chip. The light receiving device functions to convert an input signal light beam into an electric signal.
According to a fourth aspect of the present invention, the substrate further comprises another through hole defining an optical path for the light receiving device. The through hole defining the optical path for the light receiving device functions to transmit the input signal light beam therethrough.
According to a fifth aspect of the present invention, the light emitting device is a semiconductor light emitting diode. The semiconductor light emitting diode functions to convert an electric output signal into an optical output signal.
According to a sixth aspect of the present invention, the light emitting device is a semiconductor laser diode. The semiconductor light emitting laser functions to convert an electric output signal into an optical output signal.
According to a seventh aspect of the present invention, the substrate is silicon. Such a structure has an advantage of facilitating the application of circuits to the substrate.
According to a eighth aspect of the present invention, an insulator film is provided on the surface of the substrate including a side surface of the through hole. The insulator film functions to prevent an electric output signal from flowing into the substrate.
According to a ninth aspect of the present invention, the substrate is a plastic, a ceramic, a glass, a semiconductor, a metal or a graphite. The optical information processing apparatus of the present invention can be realized by using any of these materials for the substrate as in the case where a silicon substrate is used. The use of these alternative materials has an advantage that the insulator film may be a silicon dioxide film or a silicon nitride film which is provided by using a vapor deposition apparatus, a sputtering apparatus or a plasma chemical vapor deposition apparatus.
According to a tenth aspect of the present invention, an insulator film is provided on the surface of the substrate including a side surface of the through hole. The insulator film functions to prevent an electric output signal from flowing into the substrate.
According to a eleventh aspect of the present invention, the insulator film is a silicon thermal oxide film. The silicon thermal oxide film functions to prevent an electric output signal from flowing into the substrate.
According to a twelfth aspect of the present invention, the insulator film is a silicon dioxide film. The silicon dioxide film functions to prevent an electric output signal from flowing into the silicon substrate.
According to a thirteenth aspect of the present invention, the insulator film is a silicon nitride film. The silicon nitride film functions to prevent an electric output signal from flowing into the silicon substrate.
Thus, an object of the present invention is to provide a small-sized integrated optical information processing apparatus by precisely and easily producing an array of light emitting devices and optical paths for light receiving devices on a semiconductor arithmetic circuit chip.
This and other objects of the present invention will be more apparent from the following description of the preferred embodiment with reference to the drawings.